JWSS - Journal of Water and Soil Science

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Side channel spillways have a common usage in conveyance and distribution networks, high dams, water and wastewater treatment plants, and surface drainage networks. A side channel carries spatially varied flow with increasing discharge and their water surface profiles is a main feature in the design process. Usually, the bottom width of the channel is flared in the flow direction and an end sill is also installed at the downstream end to provide a control section and to generate an even water surface profile. In this study, the impact of installing an end sill on the flow characteristics in a non-prismatic side channel is presented. Six distinct longitudinal profiles were clearly observed in each run and the difference between the mid points of the maximum and the minimum profiles of each run was used to evaluate the sill effects on the water surface profile and the energy dissipation. The results indicated that the maximum and the minimum differences are, respectively, equal to critical depth and half of it generated at the channel downstream end. Also, based on an envelope of the data, a method was proposed to determine the maximum potential impact of an end sill that might have on the flow depth, which could also be considered as a guideline in the design process.

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The operation of an irrigation network is the result of a decision-making system in which three elements, i. e. the physical condition of the structures, control capacity, and hydraulic behavior of canal system, have important roles. The impact of these components is incorporated in the hydraulic sensitivity concept. For this purpose, the sensitivity of structures could be considered as the most important factor in the hydraulic characteristics of a system. The sensitivity analysis approach is one of the flow analysis methods that is used to forecast the flow behavior in several irrigation networks. Baffle Modules are one of the most suitable structures for flow regulating and delivery. In this paper, hydraulic sensitivity equations are presented for this type of structure. Also, the quantitative variations of the sensitivity index have been evaluated under operating conditions and compared with those of theoretical conditions. Then the influence of the sensitivity index variations on the performance of structures has been studied. This study was carried out on some modules of the Qazvin network. The results indicated that the hydraulic sensitivity of these off-takes varies under operating conditions. In some cases, variations were estimated to be more than 100%. The range of discharge variations was twice the predefined acceptable value (20%) in some offtakes.

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Of all types of xenobiotics, pesticides such as herbicides play a significant role in soil and water pollution due to their widely usage all over the world. This study addresses the ability of organic amendments to enhance atrazine and metamitron degradation in two herbicide contaminated soils with contrasting textures under laboratory conditions. Soil samples were collected from surface soils with textures of sandy loam and silty clay, from northeastern part of Iran. Initial concentration of herbicides was 50 mgkg^-1 soil. Contaminated soil samples were treated by manure, compost and vermicompost at the rates of %0.5 and %2 (w/w). Residual concentrations of atrazine and metamitron were determined by HPLC at the end of incubation periods of 20,40 and 60 d. Residual concentrations of atrazine were 93, 77.8 and 72.4 % of the initial concentration after 20, 40 and 60d incubation, respectively. Residual metamitron concentrations were clearly lower than atrazine. After 20,40 and 60 d., the remaining concentrations of metamitron were 5.8, 2 and 1.2 %, respectively. Organic amendments at the rates of .5 and 2 % showed similar effects on the enhancement of herbicides degradation in soils. However, no significant effect was observed between types of organic amendments. Degradation was clearly affected by soil textures. Residual concentrations of herbicides were higher in sandy loam than in silty clay soil.

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The sensitivity analysis approach should be regarded as a new means which has recently been proposed for assessing flow of the irrigation networks. This approach uses the flow steady state equations and the physical conditions of irrigation channels to evaluate the response of the system to input perturbations. In this paper, some structural hydraulic sensitivity indicators were developed and utilized in studying the flow of an irrigation channel. For evaluating the efficiency of indicators and proposed analysis method, a real case was simulated by SOBEK model. Using the simulation results and introduced indicators, the flow regulation and distribution process within channel was studied. The results indicated a successful application of sensitivity indicators in evaluating system's potential in relation to alternative operational scenarios. With the calculation of these indicators, a comprehensive information system could be provided and applied in the analysis of the response potential of channel to structural perturbations, estimation of structure setting accuracy, and in the choice of suitable operation frequency there of.

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In order to determine the effects of emulsifiers (Lecithin, E471 and E472) and their levels (0, 0.25, 0.5, 0.75 and 1%) and also addition of fungal α-amylase (0, 5, 10 and 20 g/100 kg flour) on bread staling, a completely randomized experiment with factorial design and 3 replications was conducted. Bread staling was determined after 0, 24, 48 and 72 hours of storage. Correlation between variables was analyzed by simple and multivariate regression. Results indicated that addition of emulsifiers reduced the firmness of bread. E472 had the most and E471 had the least effect on bread firmness after 72 hours of storage. Addition of α-amylase reduced the bread firmness and this effect was less pronounced after 72 hours of storage. Correlation between variables based on the development of a model showed that in the first day of bread production, optimal levels of emulsifiers were 1%, 0.25% and 0.5% for Lecithin, E471 and E472, respectively. In case of simultaneous application of emulsifiers and enzyme, the optimal level of enzyme was 5 g/100 kg flour.

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Overtopping is one of the main factors responsible for dam failure. To avoid overtopping, dam is equipped with one or some spillways to release the water impounded in the reservoir. The number and size of these spillways are determined on the basis of design flood. Determination of design flood of dam spillway can be formulated as a multiobjective risk problem. This problem can be solved by Quantitative Risk Analysis Methods. Here, four economical design methods which are based on risk analysis including, United States National Research Council (NRC), US Civil Engineering, Unit Curve and Partitioned Multiobjective Risk (PMR) were studied. In order to compare these methods, Risk Analysis was performed for re-determining design flood of Pishin Dam Spillway. This Dam has been constructed on the Sarbaz River. Owing to the fact that the integrals of the expected damage relations in the two methods, i.e., Civil Engineering, and Partitioned Multiobjective Risk are analytically unsolvable, Romberg numerical integration technique and Excel software were utilized for the related calculations and drawing graphs. Also, in order to select suitable distribution, the flood analysis was done using Smada software. The findings of the study indicated that design flood determined by the three methods, i.e., Civil Engineering, National Research Council and Unit Curve was almost the same, and that the amount of flood was less than the 10,000-year-old flood while design flood determined by Partitioned Multiobjective Risk Method, was larger than the 10,000- year-old flood.

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This study was intended to use the sourdough LAB containing specific starter cultures for Barbari bread production and reduction of its staling. For sourdough preparation, fresh microbial cells were collected by centrifugation from LAB cultures. Then 1.5% of flour (w/w) from these washed cells with the same amounts of wheat flour and tap water and 0.25% (w/w) active dry yeast extract, containing Saccharomyces cerevisiae were mixed. The effects of fermentation time (8, 16 and 24 hours), fermentation temperature (28, 32 and 36 ºC) and type of starter culture (Lactobacillus sanfransicencis, Lactobacillus plantarum and a mixture of both LAB) were analyzed in a completely randomized design with factorial experiment with 4 replications. Bread staling was determined by its measuring crumb hardness and specific volume in 1, 24, 48 and 72 hours after baking. Correlation between variables was obtained by multivariate regression, and regression models were exhibited. The results showed that sourdough had significant effect (p≤0.05) on reduction of Barbari bread staling at 1, 24, 48 and 72 hours after baking in comparison with control sample. Moreover, the sample prepared with Lactobacillus plantarum (24 h fermentation time and 32 ºC fermentation temperature) had the maximum specific volume and the least staling, 72 hours after baking.

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Among the biodiversity of soil microorganisms, bacteria have the basic role in soil functions. In order to determine the diversity and abundance of soil bacteria in arid regions, and also to study the effect of agricultural practices on them, a study was conducted in winter wheat fields on Shirvan, Mashhad and Gonabad. In each region, high and low input fields of winter wheat and a natural system for comparison were selected. Use of agricultural inputs was criteria for selection of low and high input fields in each region. Soil sampling was done on fields and natural systems and organic matter content, abundance and diversity of soil bacteria were measured in soil samples. Species richness and abundance of soil bacteria was affected by region and so that natural system of Gonabad has the minimum of species richness among the studied systems and the differences of other systems was not significant. Abundance of soil bacteria in 1 g dry soil was maximum in Gonabad and minimum in Shirvan. Abundance of soil bacteria was affected by organic matter and in low and high input systems of Gonabad and low input system of Mashhad was greater than other systems. Overall, 19 species of bacteria that belonged to 4 genus were detected. Results showed that species richness and abundance of soil bacteria in studied systems were relatively low and agricultural practices have not significant impact on these organisms, so that species richness and abundance of soil bacteria were improved in agricultural systems of Mashhad and Gonabad. Pattern of bacterial diversity showed that regional and agricultural stresses were affected on bacterial function so that in high level of stresses, species richness decreased and function of soil bacteria was restricted to decomposition of organic matter. Therefore, organic matter of soil must be increased and agricultural stresses must be decreased to improve of soil bacterial functions.

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Uprooting trees and pit – mound micro topographies are due to creation of heterogeneity condition in soil ecosystem. Pay attention to mountainous condition of hyrcanian forests in Iran and presence of trees with high diameters (old trees), therefore, it is imagined that many of trees are prone to uprooting. Thus, the aim of this research is studying variability some of soil physico - chemical characters in uprooted trees location and pit – mound position. For this purpose, twenty hectare areas of Tarbiat Modares University Experimental Forest Station studied that is located in Mazandaran province, northern Iran. Numbers of thirty four uprooted trees were found. Five microsites were distinguished including mound top, mound wall, pit bottom, pit wall and closed canopy. Soil samples were taken at 0 - 15, 15 - 30 and 30 - 45cm depths from all microsites using core soil sampler (81cm2 cross section). Soil acidity, water content, organic matter, total nitrogen and carbon to nitrogen ratio measured in the laboratory. A statistical result is indicating that the most water content, organic matter and nitrogen devoted in pit bottom. Mound top and wall included maximum of acidity. The most value of carbon to nitrogen ratio found in mound wall, as well. Soil acidity showed no significantly differences among different depths. The results of this research can be considered in forest soils survey and forest management.

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To investigate spatial variability of soil characteristics in the most valuble forest stands in the northern Iran using geostatistical approach, a twenty hectare area in Experimental Forest Station of Tarbiat Modares University was considered. Soil samples were taken from pits, mounds, canopy gaps, under single trees and closed canopy positions at 0 - 15, 15 - 30 and 30 - 45 cm depths using core soil sampler (81cm2 cross section). pH and organic matter were measured in the laboratory, and then carbons to nitrogen ratio and carbon sequestration were calculated. Spatial variability for soil characteristics revealed anisotropic variogram due to the same variability of surface variogram in different depths. pH in all the depths and carbon sequestration in 30 - 45cm depth showed exponential model whereas the other soil characteristics resulted in a linear model in different layers. The results of spatial structure showed pH with medium structure in all the depths, organic matter and carbon to nitrogen ratio with pure nugget effect (non structure), carbon sequestration in 0 - 30cm depth with weak structure and 30 - 45cm depth with medium spatial structure.

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